Critical test of bead-spring model to resolve the scaling laws of polymer melts: A molecular dynamics study

To examine the intrinsic nature of the bead-spring Kremer-Grest (KG) model, long-time molecular dynamics simulations are performed. Certain scaling laws for representative polymer properties are compared with theoretical predictions. The results for static properties satisfy the expected static Gaussian nature, irrespective of the chain length. In contrast, the results for the dynamic properties of short chains show a clear discrepancy from theoretical predictions that assume ideal chain motion. This is clear evidence that the Gaussian nature of the dynamics of short chains is not necessarily established for the actual KG model, despite it being designed to have Gaussian characteristics by virtue of its stochastic equations of motion. This intrinsic nature of the KG model should be considered carefully when using this model for applications that involve relatively short chains.